Method and apparatus for hydraulic work hardening



9 w. s. CLEVENGER ETAL 2,615,411

METHOD AND APPARATUS FOR HYDRAULIC WORK HARDENING Filed March 16, 1951 FROM HYDRAULIC PU M P FiGJE.

INVENTORS WALTON 5. CLEVE NGE R n N M m M 4 EC 0 Q 5E LD mm 5 Y B Patented Oct. 28, 1952 METHOD AlPARATUS FOR HYDRAULIC WORK HARDENING Walton S. Clevenger, Joel S. Cohen, and Sanders G. Cohen, Miami, Fla.

Application March 16, 1951, Serial noizia'oie 2 Claims.

This invention relates to the art of die forming by hydraulic pressure wherein a female die member and a pressure plate serve to clamp a sheet of stock to be formed therebetween and, by hydraulic pressure, the stock is forced into in an opening it, limits the upward movement of the ram 15. A fluid pressure conduit 20, leading from a source of hydraulic pressure, connects with the reduced bore l3 and serves to conduct the die impression and the invention has for its prime purpose a means to impact harden the material after it has been formed inthe die impression.

The invention contemplates a die forming arrangement as above indicated wherein a liquid supply is conducted to the pressure plate to force the material into the die impression and animpact cylinder having a liquid column directly communicating with the liquid within the pressure plate and a piston having a projecting head for receiving blows from a suitable tool for imparting the force of the blows directly through the liquid column to impinge upon the formed material in the die to harden the same.

Details for carrying out the invention will be more clearly described during the following description, reference being had to the accompanying drawing, wherein has been shown an example of the device and wherein like characters of reference are employed to denote like parts .throughout.

In the drawing:

Figure 1 is a central vertical section through a forming die, showing the invention applied thereto, taken on line l--l of Figure 2 and,

Figure 2 is a top plan view of the device.

Referring specifically to the drawing, the numeral 5 designates a female die member, having a suitable die impression 6, formed therein. A pressure plate 1 serves to securely clamp a sheet of material upon the upper open face of the die 5 to overlie the impression 6. The pressure plate 1, upon its clamping face, is provided with a suitable sealing medium 9 to prevent the lateral escape of fluid pressure.

An impact cylinder It, has threaded engagement within an opening H formed in the upper face of the-pressure plate 1. The upper portion of the cylinder is enlarged and is provided with an enlarged bore it, open at its upper end. The bore 12 is concentric with a reduced bore 53 that communicates with a bore 14 formed in the pressure plate I and communicating with the inner side of the plate 1. The bores l2, l3 and M are concentric 'and in alignment. Operable within the bore 12, is a piston ram l5, having a sealing ring 15', formed upon a piston rod E6. The rod l6 projects above the cylinder I0 and carries an impact head IT. A stop collar I8, threaded withvalve 25.

hydraulic pressure to the cylinder and to the die, for pressure forming the material 8. A check valve 2 dis interposed in the conduit 28 and a bypass conduit 22 communicates with the conduit 2% uponopposite sides of the check valve 2|. A suitable cut-off valve '23 is interposed in the bypass conduit. An air bleed port 24 communicates with the interior of the die through the pressure plate and is controlled by a valve 25.

In the use of the device, the sheet of material to be formedis placed over the die impression and'the pressure plate 1 brought into contact therewith and rigidly clamped in place by any suitable means, such as bolts 26. Fluid, such as oily is then introduced to the pressure plate through the conduit 20, forcing the ram [5 to its uppermost limit and filling the cavity of the pressure plate. Any air that might have been trapped in the device is released through the Continued hydraulic pressure from a pump or other source forces the material 8 downwardly into conforming contact with the walls of the die impression. Lateral escape of the oil under pressure between the work and the pressure plate is prevented by the seal 9.

. With the valve 23 closed, the oil pressure has completely filled the mold, formed the material, forced the ram i5 to its uppermost position in the cylinder and now maintains a static column of oil under pressure against the ram and the formed work. The hardening method consists of a series of rapid blows upon the head ll, either manually or mechanically and these blows are transmitted through the static column of oil to the formed material in the die, since the material is held in conforming contact with the walls of the die impression. These rapid blows are continued for a predetermined length of time, dependent upon the type of material to be hardened. The shock of the blows are prevented from travelling toward the source of the fluid pressure, by the check valve 2|. Upon a completion of the work hardening, the valve 23 is opened to permit a by-pass of the oil to its original source, suitable mechanism, not shown, being employed to reverse the fiow of the oil, after which, the pressure plate 1 may be removed and the formed object taken from the die.

It will be apparent, that a very simple and novel means has been provided to Work harden an object that has been die formed under hydraulic pressure. The mechanism is extremely;

cheap to manufacture and results in a considerable saving of time and labor costs over the old methods of work hardening by mechanical impact. In the hydraulic die, the forming medium, in this particular case, being oil, is employed as the medium to transmit the mechanical blows to the hydraulically formed work prior to its removal from the die, thus performing the complete operation of forming and hardening in a single operation. The method readily lends it self to many forms of hydraulic dies where work hardening is essential or required.

It is to be understood, that the invention is not limited to the precise structure shown, but that various changes in the shape, size and arrangement of parts may be resorted to as readily fall within the spirit of the invention or the scope of the subjoined claims.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

,1. A work hardening means for use with a hydraulic die forming device embodying a female die and a pressure plate for clamping a, work impact device connected with the pressure plate centrally thereof, th impact device and the pressure plate provided with axially aligned ports, the upper end .of th impact device being provided with a cylindrical chamber that slidably receives a ram plunger, the chamber .communicating with the ports and axially arranged therewith, a rod carried by the plunger and extending above the impact device, a head carried by the rod, a fluid pressur conduit connected with the impact device and communicating with the port for conducting fluid under pressure to the impact device and the die for forcing the work sheet into conforming engagement with the walls of the die impression, the fluid pressure forming the work sheet causing the ram to shift to its maximum outward travel, a check .valve in the fluid pressure conduit that maintains a static body of fluid in the die and the impact device after work forming, a by-pass conduit around the check valve, a valve for controlling 4 the by-pass, the ram head after the work has 4 been formed, adapted to receive a plurality of blows to be conducted to the static column of fluid by the ram, the shock of the blows impinging upon the surface of the formed work in the die, and an air relief port for the pressure plate. I

2. A work hardening impact device f-or use with the pressure plate of a female die device, comprising a body portion connected with the upper face of the pressure plate centrally thereof, the body portion terminating in an enlarged chambered head, an axia1 port formed in the body portion that communicates with the chamber and a through port formed in the pressure plate, a ram device operable in the chamber, a rod carried by the ram and projecting above the head, a hydraulicpres'sure conduit connected with the body portion and communicating with the axial port for conducting hydraulic pressure to the ram and to the interior of the die for hydraulically forming a sheet of material clamped between the die and the pressure plate, a check valve in the hydraulic pressure conduit for preventing a reverse flow of hydraulic pressure from th die and the ram after work forming, the check Valve maintaining va static column of hydraulic fluid under pressure against the ram and the formed work in the die, an air relief port formed in the pressure pl'ate, the formed work in the die adapted to receive a series of work hardening shocks imparted to the ram rod, a by-pass conduit collnected 'to the hydraulic pressure conduit upon opposite sides of the .check valve and acontrol -valvefor the by-pass. I V j WALTON S. CLEVENGER. JOEL s. COHEN. SANDERS G. COHEN;

REFERENCES GITED The following references are of record in the ,file of this patent:

UNITED STATES PATENT Date Kemerer Sept. l8," 1945 

